CS430 Midterm 1

It is not possible for several attributes to have the same domain, we require they be unique.

False

Relational Algebra is a non-procedural query language.

False

The DDL interpreter of the query processor is responsible for query optimization.

False

The order of how a tuple appears in a relations is extremely important as that is what determines the primary key.

False

The schema of a relation changes when tuples are added to the database.

False

Which of the following are representative applications of database systems?

False

The types of access for a data manipulation language are:

Insertion and deletion of data Retrieval of information

I've just added a new person to the Employee database and I did not have to alter my application that uses this database. This is an example of which type of abstraction?

Logical

Which of the following are reasons to let the DBMS manage disk space and buffer management as opposed to the OS?

Need the ability to perform special tasks such as pinning a page, pre-fetch policy, etc. Portability issues between operating systems. OS limitations - i.e. files spanning disks. PreviousNext

One domain value that is a member of any possible domain is what?

Null

In which phases does the design move from an abstract data mode to the design of the database

Physical Design Phase Logical Design Phase

I've just changed the indexing scheme for a certain database. The change is transparent to the rest of the database and other applications. This is an example of which type of abstraction?

Physical.

A ___________________ is a candidate key.

Primary Key

The output of a relational algebra operation is a single relation.

True

The person that has central control over a DBMS is called a DataBase Administrator (DBA)

True

The schema developed at the conceptual design phase provides a detailed overview of the enterprise.

True

A language in which a user specifies a database schema is called:

A data definition language

A language that is used to express database queries and updates is called:

A data manipulation language

Which statements about keys are true?

A primary key is a candidate key and a superkey

Entities are described in a database by which of the following?

A set of attributes

An instance of a relation is which of the following:

A set of tuples, also called records, in which each tuple has the same number of fields as the relation schema.

Match the responsibility to the appropriate component of the DBMS architecture. A. Recovery manager B. Transaction manager C. Lock managers

A. Ensures transaction atomicity and durability. B. Controls the execution of the transactions. C. Grants and releases locks appropriately.

Match the relational algebra name to its operation. A. Selection B. Projection C. Natural join D. Cartesian product E. Union

A. Return rows of the input relation that satisfy the predicate B. Output specified attributes from all rows of the input relation. C. Output pairs of rows from the two input relations that have the same value on all attributes that have the same name. D. Output all pairs of rows from the two input relations. E. Output the union of tuples from the two input relations.

Match the type of query language to its definition. A. Procedural B. Non-procedural

A. The user instructs the system to perform a sequence of operations. B. The user describes the desired information.

Match the database users to their definition. A. Naive Users B. Application Programmers C. Sophisticated / Specialized Users D. Database Administrators

A. Unsophisticated users accessing the system through application programs. B. Computer professionals who write packages that facilitate access for end users. C. Users who interact with the systems and/or write specialized database applications D. Professionals that design and maintain the database.

Match the component of a DBMS to its associated responsibility. A. Query optimizer B. File and access methods layer C. Buffer manager D. Disk space manager E. Transaction manager F. Lock manager G. Recovery manager

A. Uses information about how the data is stored to produce an efficient execution plan for evaluating the query. B. Supports the concept of a file, which in a DBMS is a collection of pages or a collection of records. C. Brings pages in from disk to memory as needed in response to read requests. D. Deals with management of space on disk, where the data is stored. E. Ensures that transactions request and release locks according to a suitable locking protocol. F. Keeps track of requests for locks and grants locks on database objects when they become available. G. Responsible for maintaining a log and restoring the system to a consistent state after a crash.

Match the type of key to its definition. A. Superkey B. Candidate Key C. Primary Key D. Foreign Key

A. a set of one or more attributes that allow us to identify an entity in the entity set. B. A superkey that contains no extraneous attributes. C. A candidate key that is chosen by the database designer as the principal means of identifying entities within an entity set. D. An attribute in one relation that references the primary key of another relation.

Match the relational term to its definition. A. Table B. Row C. Column Headers D. Domain

A.Collection of relations / entity set. B. Represents a relationship among a set of values / entity. C. Attributes Set of permitted values.

A relationship in a database is which of the following?

An association between entities

One very important advantage of using a DBMS is that it offers data independence. This is defined as what?

Application programs are insulated from changes in the way data is structured and stored.

A ___________________ is a minimal superkey.

Candidate Key

It is desirable for all users to see the entire logical model.

False

What are the components of the query processor?

DML Compiler DDL Interpreter Query Evaluation Engine

Which of the following are the data structures the storage manager implements as part of the physical system?

Data Dictionary Indices Data Files

A snapshot of the data in a database at a given time is called which of the following?

Database Instance

I've just added a new column to the Employee database so that I can keep track of pay rates for each employee. Which of the following have I affected?

Database Instance

I've just added a new person to the Employee database. Which of the following have I affected?

Database Instance

The logical design of the database is called which of the following?

Database Schema

A transaction is a single operation that performs multiple logical functions within a database.

False

An attribute takes a null value when the value of the attribute is computed to be zero.

False

An object-oriented data model permits the specification of data where individual data items of the same type many have different sets of attributes.

False

Data mining refers loosely to the process of semiautomatically analyzing raw input such as newspapers and field data to create reports.

False

A database schema is depicted by which of the following?

Schema Diagram

What describes the kinds of operations or transactions that will be performed in the database?

Specification of functional requirements

Typical functions of a database administrator would include which of the following?

Storage structure and access-method definition Schema definition. Security and access rights definitions.

Which of the following are shown in a schema diagram

The database schema

A foreign key is the primary key of another relation schema.

True

A query is a statement requesting the retrieval of information.

True

A query language is a language in which the user requests information from the database.

True

A relation schema consists of a list of attributes and their corresponding domains.

True

A storage manager is a program module that provides the interface between the low-level data stored in the database and the applications programs and queries submitted to the system.

True

Atomicity refers to the requirements that either all of a transaction must occur or none of it.

True

Durability refers to the fact that values within a database must survive system failures.

True

For each attribute, there is a set of permitted values called the domain or the value set.

True

Which of the following are parts of the SQL language?

View Definition Integrity Checking Data-definition language (DDL) Data-manipulation Language (DML)

Which of the following are disadvantages to file processing systems?

We must protect the data from inconsistent changes made by different users accessing the data concurrently. We must ensure the data is restored to a consistent state if the system cashes while changes are being made. Operating systems provide only a password mechanism for access control. We need special programs to answer each question a user may want to ask about the data.

How many tuples are there in a row of a table with a column header with 3 attributes?

a 3-tuple

A data dictionary contains ____________________, data about data.

metadata

A __________________ is a set of one or more attributes that uniquely identify an entity (or tuple).

superkey